1. Field of the Invention
This invention relates to novel isocyanate functional flexibilizing polymers which are compatible with a wide variety of thermoplastic or thermosetting polymeric vehicles including acrylic polymers, nitrocellulose polymers, polyurethane polymers and polyester polymers.
2. Description of the Prior Art
Thermoplastic and thermosetting film-forming vehicles such as acrylic, polyurethane, alkyd, and polyester polymers are well known in the coatings art. These materials have been applied over a variety of substrates and the formulations can be individually varied to optimize desired performance properties. In some applications, however, optimizing one characteristic such as flexibility, can adversely affect other characteristics such as hardness, durability, gloss, etc.
For painting and refinishing of automobiles and trucks a variety of thermosetting and thermoplastic film-forming vehicles are utilized including acrylic lacquers and enamels, nitrocellulose lacquers, alkyd enamels, polyester enamels, and polyurethane enamels. These materials may have sufficient flexibility for application to metal parts but they frequently will not have sufficient flexibility for the more flexible plastic-type materials utilized in automobile and truck bodies. When applied to these flexible materials, the commercial enamels or lacquers may crack, and peel off the flexible materials. Furthermore, since each of the varying enamels and lacquers may have different solvent combinations it is difficult to formulate a single additive which would provide improved flexibility for a wide variety of lacquers and enamels and yet still be compatible with the solvent systems used in such a variety of vehicles.
Prior art teachings relating to flexible compatible additives include U.S. Pat. No. 4,451,600 which describes an additive which involves a mixture of a polyisocyanate, an ester, an ultraviolet light stabilizer and an organic solvent, and U.S. Pat. No. 4,419,293 which teaches modification of a polyisocyanate by reaction with an aliphatic monohydroxy alcohol to provide improved compatability with aliphatic hydrocarbon solvents. None of these systems provide completely adequate improvements in flexibility and compatability.